This invention generally relates to the rehabilitation and improvement of utility conduits, including sewer, water, electrical, natural gas, telephone, telecommunication and similar systems. More particularly, the invention relates to the rehabilitation of conduits such that they may serve their originally intended uses while adding new functionality to the conduits.
In recent years, the industry concerned with the rehabilitation of existing water, sewage, natural gas or similar pipelines has grown dramatically as existing infrastructure is found wanting either because of its deterioration or its inability to manage the volume of materials which currently need to be transported.
A parallel, yet separate, industry, which is concerned with telecommunications cable, including high speed fiber optic lines for computer or cable television, and various other uses, is similarly expanding its capacity and reach. However, in many cases this industry is creating new infrastructure, rather than rehabilitating existing lines. The costs involved in expanding telecommunications networks are prohibitive and, unlike water systems, may be indefinitely postponed if costs are excessive. This problem is particularly acute in lower density population areas where the returns on investment in expensive telecommunications lines may be much lower than in more populous areas.
Various methods for replacing or rehabilitating existing conduits are known. The most basic method involves digging up existing pipe and replacing it length by length. U.S. Pat. No. 353,680 to Hurlbut discloses replacement pipes which have multiple chambers for carrying different media. However, the xe2x80x9cdig and replacexe2x80x9d method is extremely expensive, slow and unnecessarily disturbs the ground surface above the entire length of the conduits.
A improvement over this method essentially comprises digging an access trench or entering manholes at both ends of an old conduit and feeding a new conduit through the length of the old conduit so that the existing conduit is left as a casing around the new conduit. Some of these methods are described in U.S. Pat. Nos. 5,525,049 and 6,058,978, both to Paletta. These methods result in an easier, more efficient and cheaper conduit replacement process that does not disturb the ground above the conduit except for the access trench locations, when necessary. Methods for modifying a pipe so that is becomes a dual containment pipe are also disclosed.
Further examples of patents concerning pipe rehabilitation include U.S. Pat. No. 5,395,472 to Mandich and U.S. Pat. No. 5,971,029 to Smith et al. which concern a second replacement conduit being placed within the first replacement conduit in a two step process so that a space remains between the two liners. The space may contain, for example, a sensing system to detect leaks in the inner most conduit.
U.S. Pat. No. 4,738,565 to Streatfield et al.; U.S. Pat. No. 5,054,677 to Carruthers; U.S. Pat. Nos. 4,983,071; 5,078,546; Re. 35,271; and Re. 35,542, all to Fisk et al. disclose pipe-bursting and spreading methods and apparatuses which can be used to expand the inner diameter of an existing conduit from the inside. The existing conduit is destroyed or spread as an expansion apparatus pushes out from within the conduit and simultaneously compacts the soil which surrounds the conduit. The result is a tunnel which has a larger internal diameter than the original conduit, such that a replacement conduit inserted therein may have an internal diameter which is equal to or larger than the original conduit.
Thus, there is a need for methods for installing replacement or rehabilitating existing utility conduits while simultaneously installing new conduits suitable for telecommunications or other cables in one step, such that existing infrastructure may be utilized and multiple installation procedures may be avoided. Further, there is a need for an installation method which allows costs to be shared by multiple industries. Also, there is a need for a method for simultaneously installing multiple conduit arrangements without reducing the capacity of the original conduit. In addition, there is a need for a system which easily accommodates the needs of different industries by providing uncomplicated methods for separating multiple conduit arrangements such that they can be directed to different destinations or separate independent networks so that system access, maintenance and upgrading remains as efficient as possible.
The present invention provides a method for rehabilitating a conduit which comprises bursting a first conduit to create a tunnel, and inserting a plurality of new conduits into the tunnel, such that at least one of the new conduits has a capacity equal to or greater than a capacity of the first conduit.
The invention further provides a method wherein the new conduits are inserted simultaneously and are either separate from or removeably connected to one another, such that the new conduits are capable of being diverted from the tunnel at separate locations.
In accordance with another preferred embodiment a method for rehabilitating a conduit which comprises bursting a first conduit to create a tunnel, and inserting a new conduit into the tunnel, the new conduit comprising a plurality of channels, such that at least one of the channels has a capacity equal to or greater than a capacity of the first conduit.
In other preferred embodiments the invention provides methods for simultaneously inserting multiple conduits for various uses into an existing conduit.
The invention further provides methods and related apparatuses for bursting existing conduits to create tunnels, installing new conduits into the tunnels and diverting the new conduits or conduit channels from one another such that they can be directed to different locations.
The invention further provides a junction between two multi channel conduits and a multi channel conduit with an outer annular region which is particularly suitable for drilling such that a central bore may thereby be accessed.
Other objects, features and advantages of the present invention will be apparent when the detailed description of the preferred embodiments of the invention are considered in conjunction with the drawings, which should be construed in an illustrative and not in a limiting sense.